1. Technical Field
The invention relates to debugging in a multitasking operating environment of a computer system and more particularly to a debugging program execution of which has a minimal effect on operating system timing. Still more particularly, the invention relates to a debugging program which may be entered through the keyboard interrupt without a reboot of the operating system.
2. Description of the Related Art:
Computers, programmed with appropriate application programs, are to most users a tool. Application programs apply to the user's work, such as programs that do inventory control or word processing. However, application programs cannot be directly executed on a general purpose personal computer. An operating system is required between the computer hardware and the application program for controlling the processor which executes instructions, memory which stores instructions and data, and input/output devices through which the computer is programmed and through which it displays results.
An operating system is a collection of related processes on a computer system which provide an environment for the execution of application programs. In a multitasking operating system, as provided by the OS/2.RTM. operating system available from International Business Machines Corporation, processes provide a number of tasks such as resource allocation between competing applications, synchronization of data streams and management of data files in memory. Typically, a large part of application program development involves assuring that an application program works with the operating system. One aspect of compatibility is a requirement that certain events occur in proper sequence. In other words, timing must be right.
Application program developers typically use operating systems which include large debugging program modules. For a number of reasons, these debugging program modules are not typically included with operating systems sold with computer systems at retail. Most users would have little use for this module and its presence in the operating system can slow system responsiveness. However, its removal occasionally disrupts timing relationships between application programs and the operating system in unforeseen ways. Thus a user may encounter problems which are not reproducible on a system incorporating the debugging program module.
Application problems with an operating system can appear to the user as a keyboard problem. The problem manifests itself by the computer appearing to refuse inputs from the keyboard, and thus the system appears to "hang up". Frequently, the problem actually lies elsewhere. Accordingly, it would be useful to have a tool which establishes that the keyboard is active without destroying the conditions on the system through a soft reboot of the operating system. The tool should permit evaluation of the keyboard mechanically.